Reciprocal

I've always felt that LSD is barely better than nothing. Have you ever jacked up the rear end, turned one wheel while someone held the other? There's not much torque transferred by the tiny springs and friction pads of a LSD. They wear out, and most people would never know they are worn out because they do so little. Have you ever pulled the gear, or changed one in your cars? The Eaton (self) locker is an interesting device, works well in trucks and such, but because the engagement is abrupt, it's not suited for sports cars. Therefore, back to LSD and diddly squat for it's actual effect on traction.

Having LSD in the '10 is one thing, retrofitting to the older cars is something I would not do even if I strongly believed in LSDs (which I don't), but because disabling VDM gives up a valuable safety feature, and it's not calibrated to the LSD if you leave VDM enabled.

teoh2005

This is the reason Lexus did not make a Diff standard in 08/09. Lexus believed that most of its target buyers would not appreciate/need one. I firmly believe any rear wheel driven sports car/sedan should have one standard. It DOES make a difference and a huge one especially if you have driven on a track. For those that think its a waste or not needed have never even come close to the limit of traction where a LSD/TBD is needed.

Also as for LSDs, yes they wear/break and can make noticeable noise but TBDs (the one Lexus is adding to 2010) do not need maintenance as they are gear not clutch driven and are quiet. Also you can leave VDIM enabled and it won't affect the TBD in day to day driving but to exploit its full effect VDIM should be turned off. If you are not willing to turn VDIM off, that means you dont track/can control the car and don't need a LSD/TBD.

-Kevin

bnizzle87

lexus gauged its target consumer to be more daily driver yet sporty luxurious feel when it created the IS F. to update the model with a LSD only suits those who wish to take their F to the tracks, but for those who do not, of course the LSD proves meaningless. its just a matter of driving preference and maybe a lil more enthusiasm when it comes to the racing aspect of this car. at least the warranty wont be voided if we leave VDIM off, unlike the nissan GT-R

lobuxracer

iTrader: (2)

OK, time to stop the stupidity. It is IMPOSSIBLE to turn off VDIM, no matter WHAT you do. VSC and TRAC can be disabled. The electronic limited slip CAN NOT BE SHUT OFF. Neither can ABS, EBFD, and brake assist. VDIM describes ALL these features used in an integrated fashion instead of standalone implementation.

So you will NEVER get 100% of the car's nannies shut off. EVER. You can't even disable the skid control ECU because it controls brake bias electronically, so you'd be at a single fixed brake bias (and likely not a good track or street compromise for anything but getting groceries).

I pored over the entire suite of VDIM features and implementation when I got my '06 350, and I've read every update since. I originally posted the chart JoeZ put up describing what is off and on with the different switch settings.

So, to recap:

VDIM - can NEVER be turned off
ABS/EBFD/BA - can NEVER be turned off
VSC - can easily be turned off with a switch or the pedal dance
TRAC - can easily be turned off with a switch or the pedal dance

Audriuss

Thanx for putting all in one piece!

Maybe you could tell, if any of electronic devices/programs or anything connected would be afected if LSD from 2010 IS-F would be fittet?

teoh2005

In this thread VDIM has been used interchangeably when Trac was intended. Yes ABS and Brake Assist can never be turned off so then VDIM can never be completely turned off. However Trac which is the electronic braking differential/electronic LSD can be turned off and stays off using the pedals not the long push. Shutting off Trac is the only item that really matters when a diff is involved. Even if Trac is left on it will have minimal effect on the function of the TBD. Reading technical articles is one thing, testing real world applications is another.

-Kevin

FisforFast

Beats the purpose of a mechanical LSD if you can't turn the electronic one off. Makes it a useless feature, like a cigarette lighter

lobuxracer

iTrader: (2)

Right. Reading the manufacturer's documentation trumps all. That's where I get my information. Ask any A&P certified aircraft mechanic why this is important.

teoh2005

Yes according to the 08 IS-F manual, "Electronic LSD" can't be shut off via long push b/c it can still flicker (showing that its working). Where is the documentation on the pedal sequence and its effects (nowhere to be found in the manual)? I've used the pedal sequence and the Traction Icon does NOT flicker = no electronic LSD working. Have you actually tested this?

Lexus does a good job of writing its manuals, it keeps in mind its core audience of those who need to keep all safety nets in place for intended street use and not track use. Lexus (probably for legal reasons) does not want its customers to be able to completely turn off Trac, slide off the road, and sue them b/c "the traction control should always be on." Back to the original point, people were concerned if the retrofit of the TBD could be possible. Christian has confirmed that a retrofit of a Tom's LSD is possible with no issues. So where is there any potential issue of putting a TBD in the 08/09 models? Can anyone actually confirm that there will be any problems?

-Kevin

lobuxracer

iTrader: (2)

The weather in Atlanta hasn't been conducive to any kind of testing over the last week. I will definitely be testing what you've discovered since it could mean there is a way to shut off all VSC, TRAC, and electronic LSD intervention. If we can do that, then yes, a TBD or a clutch-type LSD will work without any question or worries.

No one here can answer the question "will this work without problems" today. I'd love to have a conversation with the team who wrote the skid control software, it would surely give us what we'd all like to know. It might also be helpful to have a conversation with the guys who built the IS-F racing at the Nurburgring this year.

teoh2005

Just took 2 quick videos to illustrate my point. In them I take the same 3 turns and halfway through the turn I apply full throttle to break traction.

Video 1: VSC/TRAC turned off Via Long Push
http://www.youtube.com/watch?v=DnDE0c8axwA
-As you can see in all 3 turns the VSC/TRAC ICON DOES Flicker meaning VSC/TRAC is not fully disabled. This method can be found in the IS-F manual.

Video 2: VSC/TRAC turned off Pedal Sequence
http://www.youtube.com/watch?v=lkbR13gEiyo
-In this video in all 3 turns the VSC/TRAC ICON DOES NOT Flicker meaning VSC/TRAC and most importantly "electronic lsd effect" are TURNED OFF. This method is nowhere in the manual.

Like I said Lexus is only going to tell its customers so much. They know their target audience and do not feel comfortable with their customers driving around w/out any kind of traction control. Other car manufacturers have different views on this and setup their systems as such. Can't always believe whatever is in the manual is the complete truth.

-Kevin

oztiks

Anyone done a torsen swap, yet?

chrisburke

i need time... anyone have any extra. otherwise it would be on the car.

Christan

Guys, what is the status on this? Has the torsen parts become available yet? I have changed my suspension and i can tell you this for sure, that it has made a huge difference. With the differential on track, i know i can post better times.. im almost tempted to get the clattering clutch type..

anajri

so let me gget this right
with the pedal dance does the car go sideways o no?
whats the sequence for the dance again? let me try this out?
alf